I have a 1970 Buick Skylark custom. The car was originally a drum brake car.sometime before I bought the car it was switched to front disc.the people that did the work missed some details with the hydraulic system. The hold off valve was missing. I'm replacing all the brake lines with stainless lines from classic tube. They told me that the brake line that goes to the rear of the car is made of two sections. The sections are joined by a connector. My old brake line does not have a connector.did the disc brake cars have a connector in this line or was it some other type of hydraulic fitting. Thanks for the help. Joe
No, Chevelle's use a two piece rear brake line. All Skylarks and GS's regardless of disc or drum use a ONE PIECE line. They will insist your car has a factory two piece line. It doesnt
Yup just replaced my brake line on my 72 GS455, it is one piece from the rear end to the front at the proportioning valve .
Oh, and good luck replacing that rear brake line without taking the body off the frame. If there's nothing wrong with it, I would just leave it alone.
As I understand 71 and 72 Incorporated the hold off valve and the proportional valve in one unit. So those years would have a one-piece brake line. Interesting enough the Buick manual only shows the hold off valve. It says nothing about a proportional valve. Talking to these guys classic tube and the right stuff can be very confusing. Seems to be a lot of controversy online about this as well. Not all a body cars came with the two-piece brake line and a rear proportional valve in 1970 from what I'm finding. Is that your understanding as well?
I think all cars with Front disc brakes and rear Drums NEED to have a proportioning valve for correct function?
What I am trying to find out is "in 1970 did Skylarks with factor power disc brakes come with a proportional valve on the rear. I do not find it in my repair manual. I did find the hold off valve in the repair manual. I do agree that adding a proportional valve, to the system will keep the rear wheels from locking up in a hard braking situation. The only ones I can find aside from the combination hold-off /proportional valve combo is the adjustable proportional valve.
The 1970 disc brake cars had the same distribution block the drum brake cars had on the frame below and slightly behind the master. The disc brake cars also had the hold off valve attached to the master. Drum brake cars continued to use the same distribution block in 1971 and the disc brake cars deleted the hold off valve and incorporated a proportioning valve in place of the distribution block. Use the original distribution block with a hold off valve or switch the distribution block for a 71-72 proportioning valve.
https://www.ss396.com/chevelle/FPR-107.html https://www.opgi.com/brake-systems/...lve-front-disc-brake-1970-a-body-ch28188.html
No to highjack the thread but I also have a 70 skylark custom, except mine already has the front discs and does have the hold off valve. I want to jsut add rear discs, can I just swap in a rear kit then? or do I have to get another prop valve? I don't want to have to add or modify the lines too much since they all appear to be in great condition as well.